<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登陆页面</title>
    <style>
        /*重置样式*/
        *,
        *:after,
        *:after{
            margin: 0px;
            padding: 0px;
            box-sizing: border-box;
        }
        html{
            width: 100%;
            height:100%;
        }
        body{
            width: 100%;
            height: 100%;
        }
        .container{
            width: 100%;
            height:100%;
            position: relative;
        }
        .container .container_loginbox{
            width: 400px;
            height:400px;
            background-color: lightblue;
            position: absolute;
            top:50%;
            left:50%;
            margin-top: -200px;
            margin-left: -200px;
        }

    </style>
</head>
<body>
    <div class="container">
        <div class="container_loginbox">
            <form action="" method="post">
                <label>
                    姓名：<input type="text" placeholder="请输入姓名" name="username"><br>
                    密码：<input type="password" name="password"><br>
                    <input type="submit" value="登陆">
                </label>
            </form>
        </div>
    </div>


</body>
</html>